feat(skills/settings): 技能复制 + 设置持久化等会话前改动

- 技能复制:新增 POST 复制接口(_rewrite_skill_frontmatter_name 重写 frontmatter name + 校验 + 去重),前端 skills api/hooks 与技能设置页配套
- 设置持久化:lastAgentId、线程 RAG 模式锁(settings/index、local)
- i18n(en/zh/types)、agent-card/input-box/message-list 等页面文案与交互微调
- scheduler/element.py 小修

(本批为会话前已存在的工作区改动,按要求一并提交;构建产物 backend.zip 未提交)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

offline-backend-20260512/backend/app/gateway/routers/skills.py

@@ -30,7 +30,7 @@ from deerflow.skills import Skill
 from deerflow.skills.cascade import cascade_skill_unpublished_or_deleted
 from deerflow.skills.installer import SkillAlreadyExistsError
 from deerflow.skills.security_scanner import scan_skill_content
-from deerflow.skills.storage import get_or_new_skill_storage
+from deerflow.skills.storage import SkillStorage, get_or_new_skill_storage
 from deerflow.skills.types import SKILL_MD_FILE, SkillCategory
 
 logger = logging.getLogger(__name__)
@@ -210,6 +210,12 @@ class CustomSkillUpdateRequest(BaseModel):
     content: str = Field(..., description="Replacement SKILL.md content")
 
 
+class SkillDuplicateRequest(BaseModel):
+    """Request model for duplicating an existing skill into a new custom skill."""
+
+    new_name: str = Field(..., description="Name for the new custom skill copy (lowercase letters/digits, '-'/'_' separators)")
+
+
 class CustomSkillHistoryResponse(BaseModel):
     history: list[dict]
 
@@ -950,6 +956,121 @@ async def install_skill(
         raise HTTPException(status_code=500, detail=f"Failed to install skill: {str(e)}")
 
 
+def _rewrite_skill_frontmatter_name(content: str, new_name: str) -> str:
+    """Return *content* with the YAML-frontmatter ``name:`` field set to *new_name*.
+
+    A duplicated skill must declare the new name in its SKILL.md frontmatter or
+    ``validate_skill_markdown_content`` will reject it (frontmatter name must
+    match the directory name). We rewrite only the first ``name:`` line inside
+    the leading ``---`` block, leaving every other field byte-for-byte intact.
+    """
+    match = re.match(r"^---\n(.*?)\n---", content, re.DOTALL)
+    if not match:
+        raise ValueError("SKILL.md is missing the leading YAML frontmatter block")
+    fm = match.group(1)
+    new_fm, replaced = re.subn(r"(?m)^(name:\s*).*$", rf"\g<1>{new_name}", fm, count=1)
+    if replaced == 0:
+        new_fm = f"name: {new_name}\n{fm}"
+    return content[: match.start(1)] + new_fm + content[match.end(1) :]
+
+
+@router.post(
+    "/skills/custom/{source_name}/duplicate",
+    response_model=SkillInstallResponse,
+    summary="Duplicate Skill",
+    description=(
+        "Copy an existing skill (built-in/public OR custom) into a brand-new custom "
+        "skill named ``new_name``, owned by the caller and unpublished. All support "
+        "files are copied verbatim; only the SKILL.md frontmatter name is rewritten. "
+        "The source already passed the install-time security scan, so no re-scan is run."
+    ),
+)
+async def duplicate_skill(
+    source_name: str,
+    body: SkillDuplicateRequest,
+    request: Request,
+    config: AppConfig = Depends(get_config),
+    skill_store: SkillStore = Depends(get_skill_store),
+) -> SkillInstallResponse:
+    import shutil
+
+    try:
+        user_id = _current_user_id(request)
+        is_admin = _is_admin_user(request)
+        storage = get_or_new_skill_storage(app_config=config)
+
+        source_name = SkillStorage.validate_skill_name(source_name.replace("\r\n", "").replace("\n", ""))
+        new_name = SkillStorage.validate_skill_name(body.new_name.replace("\r\n", "").replace("\n", ""))
+
+        # Resolve the source directory (custom takes precedence over public, so a
+        # user-shadowed copy is the one duplicated when both exist).
+        if storage.custom_skill_exists(source_name):
+            source_dir = storage.get_custom_skill_dir(source_name)
+        elif storage.public_skill_exists(source_name):
+            source_dir = storage.get_skills_root_path() / SkillCategory.PUBLIC.value / source_name
+        else:
+            raise HTTPException(status_code=404, detail=f"Skill '{source_name}' not found")
+
+        if new_name == source_name or storage.custom_skill_exists(new_name) or storage.public_skill_exists(new_name):
+            raise HTTPException(status_code=409, detail=f"A skill named '{new_name}' already exists")
+        if not is_admin:
+            existing = await skill_store.get_any(new_name)
+            if existing and existing.get("owner_user_id") not in (None, user_id):
+                raise HTTPException(status_code=409, detail=f"Skill '{new_name}' already exists and is owned by another user")
+
+        dest_dir = storage.get_custom_skill_dir(new_name)
+        # copytree refuses to overwrite, which is the behaviour we want — the
+        # existence checks above already guarantee a clean target.
+        shutil.copytree(source_dir, dest_dir)
+        try:
+            source_content = (dest_dir / SKILL_MD_FILE).read_text(encoding="utf-8")
+            new_content = _rewrite_skill_frontmatter_name(source_content, new_name)
+            SkillStorage.validate_skill_markdown_content(new_name, new_content)
+            storage.write_custom_skill(new_name, SKILL_MD_FILE, new_content)
+        except Exception:
+            # Roll back the half-created directory so a failed copy never leaves
+            # an unparseable skill on disk.
+            shutil.rmtree(dest_dir, ignore_errors=True)
+            raise
+
+        await skill_store.ensure_legacy({"name": new_name, "owner_user_id": user_id, "published": False})
+        try:
+            storage.append_history(
+                new_name,
+                {
+                    "action": "duplicate",
+                    "author": "human",
+                    "thread_id": None,
+                    "file_path": SKILL_MD_FILE,
+                    "prev_content": None,
+                    "new_content": new_content,
+                    "source_skill": source_name,
+                },
+            )
+        except Exception:
+            pass
+        try:
+            from deerflow.skills.usage import mark_uploaded
+            mark_uploaded(new_name)
+        except Exception:
+            pass
+        await refresh_skills_system_prompt_cache_async()
+        return SkillInstallResponse(
+            success=True,
+            skill_name=new_name,
+            message=f"Skill '{source_name}' duplicated as '{new_name}'",
+            overwritten=False,
+            category=SkillCategory.CUSTOM.value,
+        )
+    except HTTPException:
+        raise
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    except Exception as e:
+        logger.error("Failed to duplicate skill %s: %s", source_name, e, exc_info=True)
+        raise HTTPException(status_code=500, detail=f"Failed to duplicate skill: {str(e)}")
+
+
 @router.post(
     "/skills/reconcile-custom",
     response_model=SkillReconcileResponse,